Image processing tech boosts LCD power efficiency

Power saving is an important concept in the flat-panel display industry. For example, the California Energy Commission recently approved an energy efficiency standard for televisions. When the standard is implemented in 2011, new TVs sold in California should consume at least 33 percent less electricity. Likewise in China, the world's largest TFT-LCD TV market, a similar energy-saving concept has been advocated at various events. However, with current power-saving technologies, there is always a conflict or trade-off among power-saving, image quality, and the costs to achieving both goals. To optimize energy efficiency, panel and system makers are aggressively seeking the best solution which has promised a bright future for green technologies.

TFT-LCD backlight, either CCFLs or LEDs, typically maintains a constant brightness at all times, regardless of the displayed images. One commonly-adopted technique in saving backlight power is content adaptive backlight control which dynamically adjusts the backlight and contents. While this pure digital approach is able to save panel power, it inevitably leads to loss in gray scales while adjusting gamma curve and thus an undesired image quality. These side effects could be mitigated by using 10bit or higher TFT-LCD panels, as adopted by a few Japanese tier one TV brands. However, higher bit TFT-LCD panel also leads to higher costs, which prevents wide adoption.

"Compared to conventional pure digital image processing in timing controller and video processor, iCT is an innovative mixed-mode image processing technology which not only enhances image quality, but saves up to 50 percent of panel power in certain image contents," said Linkai Bu, chief technology officer of Himax Media Solutions. "Tier-one TFT-LCD panel makers and system makers world-wide are highly interested in adopting iCT in their products as they expect iCT will be one of the key differentiators for their next generation TFT-LCD TVs and monitors, some of which are expected to hit the market by mid 2010. In relation to iCT and its associated image processing know-how, Himax has filed more than 30 patents in Taiwan, China, and the United States."

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